Chang Y.-TLee M.-HChu M.-WCHIH-HSUAN CHEN2022-11-162022-11-16202225900498https://www.scopus.com/inward/record.uri?eid=2-s2.0-85125017663&doi=10.1016%2fj.mtadv.2022.100223&partnerID=40&md5=baefde22afd85682061ccadc1ddc1a44https://scholars.lib.ntu.edu.tw/handle/123456789/625487The microstructures and phase formations of Ti20Zr15Hf15Ni35Cu15 high entropy shape memory alloy (HESMA) under different aging conditions were investigated in this study. At aging temperatures below 500 °C, a large amount of the H-phase formed, and the martensitic transformation temperatures were suppressed due to the strain field around the H-phase. Aging treatment at 600 °C caused a eutectoid reaction, which yielded a lamellar structure composed of (Zr,Hf)7Cu10 and Ti2Cu phases. When the aging treatment was increased to 700 °C, the lamellar structure was no longer observed, but (Zr,Hf)7Cu10 and newly-formed Ti2Ni phases formed around the original Ti2Ni phase. Experimental results demonstrated that the H-phase precipitation, eutectoid decomposition, and (Zr,Hf)7Cu10 formation occurred at different aging temperatures. These results could be utilized to adjust the martensitic transformation temperatures and design microstructures, providing a new strategy for developing TiZrHfNiCu HESMAs. © 2022 The AuthorsEutectoid reaction; High entropy alloy; Martensitic transformation; Precipitation; Shape memory alloyBinary alloys; Copper alloys; Entropy; Hafnium alloys; High-entropy alloys; Lamellar structures; Precipitation (chemical); Shape-memory alloy; Titanium alloys; Zircaloy; Ageing treatments; Aging conditions; Aging temperatures; Eutectoid reaction; High entropy alloys; Large amounts; Martensitic transformation temperatures; Microstructure formation; Phase formations; Strain fields; Martensitic transformationsjournal article10.1016/j.mtadv.2022.1002232-s2.0-85125017663